When I did my bearings last January, I bought a 150 gram tube of grease from the local dealer and weighed out half into an old butter container, then put the other half in another container. I then packed the bearings, coated the spindle and races, and put the remainder into the grease cap. 7 months later I haven't had any problems with overheating or anything like that.
At time time, I was told that the M-B grease was special and to use it specifically. Given that the grease wasn't expensive, I don't see anything wrong with using it.
Just my $.02...good luck!